Well, everyone wants to control his thoughts and most of us will agree it is not that easy.
Have you ever played with a cute baby?
Were you able to control that baby? If yes, you can control your thoughts easily.
Your mind is like that one-year-old baby.
If you observe, a baby will always need something to play with. Any object will do the work.
Sometimes the baby might have grabbed your cell phone. But, as you didn't want the baby to play with your costly cell phone, you placed the keys of your car in its hands and took the phone away.
In the same way, your mind can not be empty. You can not stop your thoughts. You just can divert your thoughts.
Let's understand it with an example.
In case of workload, you will be worried about finishing that task before the deadline. Your mind will not stop worrying until and unless you give it another thought to think about. And that thought should be about the fun you will be having after the completion of your work. You will feel better with those thoughts.
In the same way, you can replace your all thoughts. With this trick, you can convert your sadness into happiness instantly. You can be optimistic. Nobody can hurt you. You can easily move on from a breakup. Failure can not demotivate you.
You just need to think about the right thought to give your mind to think about that thought.